It was one thing when Facebook surpassed a billion users. That apparently happened in October 2012 and in some circles it was relatively easy to dismiss. Dead people, people with multiple accounts, people who signed up but never logged in, you name it.

In fact, back then, even CEO Mark Zuckerberg acknowledged the company was going through tough times. A poorly executed IPO and seeming lack of a mobile strategy was holding the company back.

But on Monday, August 24, 2015, one billion people used Facebook in a single day. As the title says, that’s one in seven earthlings checking in to say happy birthday, prepare for National Dog Day, or get in touch with people they hadn’t seen in years. That number is VERY hard to ignore.

Retailers have been grappling with what to do with this phenomenon for years, and in typical retailer fashion have run the gamut from “let’s sell stuff ” to “meh…just throw up a page and let it be… there’s no money there. ” And back again.

In fact, newly minted fellow Forbes blogger (and RSR partner) Nikki Baird pointed out this week that in some cases, retailers have lost control of their own Facebook pages. And as she so aptly put it, “Retailers… like it or not, have Facebook pages for their local stores. ” Nikki does a great job discussing the different strategy retailers can use for their local store pages, but we also have to address more general questions: “Can Facebook really help my brand? Will it ever become a viable shopping channel? “

The answer to the first question is: “Definitely ” and to the second: “It doesn’t matter. “

Every year I watch the Oscar telecast (does that make me old, I wonder?) It’s always boring, and has been so for as long as I can remember, but I still tune in every year. In fact, just in the US, more than 43 million people tuned this year. I seem to remember hearing that a billion people watch around the world, but that might be hyperbole. In any case, there’s no lack of advertisers on Oscar night. According to USA Today 31.1% of viewers who watched the Oscars in 2014 were more likely to buy the brand after seeing its Oscar show. That’s way higher than Superbowl viewers (6.9%). Who knew?

Thinking about this, I decided to see if there’s any kind of ROI in Facebook advertising. I found some really interesting data in Adweek. The article found that even though Facebook advertising has become more expensive year-over-year, ROI was going up too. To quote marketing research analyst Laura Ruskowski:

“While cost increased significantly, return on investment increased significantly over the period, as well, with retailers seeing a return on investment nearly two times more in 2014. “

And that was close to a year ago, or close to a decade in “Facebook years. “

A billion people. A single day. Global retailers. Seriously guys: is this not the single biggest forum you could ever hope to reach? Do you need a “buy button ” to feel like you got an ROI?

In other words, Facebook is the biggest audience you’re ever going to find on one place. Ever. Just the tiniest bit of targeting will bring targeted results. Now, I’m not talking about the ever-irritating re-targeting efforts (Overstock.com… I bought the rug! From you! Stop showing it to me already!!) I’m talking about fresh, specific advertising and promotion to an audience that wants to be there.

I know that Pinterest and Instagram are considered cooler. But I’m not sure either of them can boast those kinds of numbers across such a variety of demographics. Facebook is a real community. People mourned with COO Sheryl Sandberg when she lost her husband suddenly and unexpectedly. They celebrated with Mark Zuckerberg when he announced his wife is pregnant. They rejoiced (or not) when the Supreme Court handed down its historic decision on same-sex marriage. They honor births and marriages and say hello to old and new friends.

You can’t afford not to be there. It’s just that simple. Global retailing coupled with a global community. It doesn’t get any clearer than that.